Shielded radio receiving apparatus and the like



July 28, 1931. w, BQND 1,816,718

SHIELDED RADIO RECEIVING APPARATUS AND THE LIKE Filed Feb. 19, 1930 2Sheets-Sheet l Inventoh:

Willi a'rn L1.Bond,

by MW His Attorney.

July 28, 1931. w. L. BOND 5 1,816,718

SHIELDED RADIO RECEIVING APPARATUS AND THE LIKE Filed Feb. 19, 1930 2Sheets-Sheet 2' I r Li' 58 Z STAGL'fl 30 l7 l7 Fig.5. Z2 Z8 Z0 Z8 I F FIB 48 42 27 49 lnvencor WiLLi am L. Bond,

y MW His Attorney.

Patented July 28, 1931 Uni-WE STATES MEN-T orricst WILLIAM: L. BOND, (3FSCHENECIADY, li-EWj YGRK, ASSIGNOR TO' GENERAL ELECTRIC COZYIPANY, ACORPORATION OF NEN YORK SHIELDED RADIO RECEIVING APPARATUS AND THE LIKEApplication filed February 19, 1930. Serial 116 429357.

The present invention relates to shielded radio receiving apparatus andthe like, in which metallic shielding is arranged to surround theapparatus and to protect it not only from external electricalinfluencestend ing to create disturbingimpulses in the various circuitsof the apparatus, but also from undesired electrical coupling betweenthe component parts of the apparatus, such as the tuning inductances,for example. Such electrical coupling may be both electrostatic andclectro-magnetic, or either one of them.

In modern receiving apparatus and the like, embodying high gainradio-frequency amplifiers, such as screen grid amplifier tubes forexample, the shielding of the component parts from each other bymetallic envelopes or shields has become increasingly important andvarious types of shielding are now in use for that purpose. Examples ofextensive and effect ve shielding means for high gain amplifiers may befound in the copending application of Albert V. Hull, Serial N0.166,773, filed February 8, 1927, and in the patent to Harry C. Thompson,1,659,52, both of which are assigned to the same assignee as the presentapplication. Such shielding mcv often be complicated in construction,costly, and unadapted for manufacture in quantities. Its effectivenessdetermines to a large extent the sensitivity or amplifying power or" theapparatus for which it is provided.

in modern receiver design and in the design of radio apparatus of thistype, intended -for commercial use, the problem of cost reduction andadaptability to quantity production is important and must be consideredalong with the problem of providing adequate and eil'ective shielding.It has been'iound that while it is comparatively easy to provide anelaborate and expensive shielding to gain effectiveness, it is much morediihcult to provide the desirable and necessary features of an effectiveshield in a construction adapted for commercial and quantity production.

It is, therefore, the primary object of the present invention to provideashield construction for radio receiving apparatus and the like,embodying high gain amplifiers such as screen grid tubes, which includesthe desirable and necessary shielding features 111 anefi'ective andeconomical manner.

It is afurther object of the present invention to provide an effectiveandeeonomicali shield of the above type havinga base which forms a.frame or chassis for the apparatus for which the shielding is providedand is amajor elementofthe shielding for such apparatus; In certainapparatus havmg a multiple tuning means such as a gang condenser orcapacitor, it is a further object of theinvention to utilize the frameof such capacitor as the chassis or base above defined. 1

The invention will be better understood and other objects and advantagesthereof will be apparent from the following description, when taken ineonnection with the accompanying drawings, and its scope will be pointedout in the'appended claims.

In the'drawings, Fig.1 is a front view in perspective of the assembly ofa shielded radio receiving apparatus embodying the in- 17611171011; Flgi2 1s a slmilar view of the rear of the apparatusof Fig. 1 with parts ofthe shielding raised to expose the interior there,- of; Fig. 3 is aninterior plan view of the apparatus as shown in Fig. 2 with parts of theshielding removed; Fig. 4 is a sectional view of the apparatus takenalong line M of Fig. 3 in the direction of the arrows and showing themanner in which the input circuit of each tube is shielded from itsoutput circuit; Fig. 5 is a similar view taken along line 5-5 of Fig. 3in the direction of the arrows showing the manner in which inductancedevices in the apparatus are shielded from each other, and Fig. 6 is aschematic wiring diagram of a radio receiving apparatus embodying amulti-stage high-gain radio-frequency amplifier which the shield of thepresent example is adapted to, enclose.

Referring to Figs. 1 to 5 of the drawings, in which the same referencenumerals are applied to like parts, 9, 10, and 11 are the statorsections of a multiple tuning capacit'or having a common rotorcomprising sections 12 carried by a common shaft 13. The shaft isjournalled in suitable bearings 14 I (Fig. 2) provided in the ends of arectangular metallic frame 15 and is driven by a tuning drum 16. This isa common form of tuning means for a radio receiving apparatus and mayinclude any desired number of sections corresponding to the number oftuned circuits employed in the apparatus. 7 Connected with each sectionof the tuning capacitor and providing therewith a tuned circuit, is aninductance or winding 17. In the present example three inductances areshown and together with the tuning capacitor having the same number ofsections represent any number of suitable tuning ele ments for a radioreceiving apparatus. The tuned circuits provided by the associatedinductances and tuning capacitormay be connected in any suitable manner.to tune the apparatus. In the present example they are arranged toprovide successive tuned circuits in a multi-stage radio frequencyamplifier and detector apparatus for a radio re ceiver. As the remainderof the radio apparatus, including the output circuits and supplycircuits, do not concern the present .invention, the. same are notshownin the drawings.

For use in a radio receiving apparatus of .the above type, the tunedcircuits formedby the associated inductances and tuning capacitor areadapted to be connected with the input or control electrodes of electricdischarge devices such as screen grid tubes 18, 19 and 20, and for thispurpose are provided with output leads 21 and terminal means or caps 22for connection with the control electrode terminals 23 of such tubes.Suitablecircuit' terminal means, such as tube socxets 2 1, are providedformounting the .tubes, and include contact terminals 25 for makingconnections with the tube base prongs or terminals 26 in the usualmanner. 3 The circuit terminals are provided with suitable outputcircuit leads 2'? and are adapted to connect with supply leads (notshown). lVith this arrangement, the tubes 18, 19 and 20"are eachconnected with a tuned input circuit including an inductance and avariable capacitor section and with output circuit leads 27, andrepresent by way of example, a series of tuned amplifier circuitslorstages for a radio receiving apparatus as hereinbefore mentioned. Thetwo stages represented in the present example may be designated as thefirst or input and the second or intermediate stages, as noted in corn'nection with Fig. 4. It will be seen that these stages overlapphysically and that an :output tube is located in the second stage.

Forthe purpose of illustrating the com- .plete high frequency amplifyingand detecting system of a radio receiving apparatus,

A the tube 2Q included with the secondstage may be considered to be adetector, while the stages containing tubes 18 and 19 are radiofrequency amplifier stages of the high gain type, screen grid tubesbeing employed therein. a

The stages shown are connected in cascade by connecting he output loads27 of the first and second stages with high inductance primary windings28, associated with the successive inductance windings 17 as indicatedin the drawings, particularly 2, 8 and 5. It is evident that the outputleads of the tube 20 of-the present example may be connected in asimilar manner to a similar tuned output means. However, with this tubeemployed as a detector, the output leads therefrom are connected withthe remainder of the receiving apparatus (not preferably through a highfrequency cnolre coil 29. c High frequency energy to be amplified anddetected is suppliedto the first stage through slitable means such as acoupling windingtlO associated with the winding 17 tube 18 in inductiverelation thereto. The circuitarrangement of the above de scribed radioreceiving apparatus embodying high frequency, tuned amplifier of the lgh gain screen grid type will be clear from a consideration. of atypical eircuitdiagrain for the same shown in Fig. 6, to which, alongwith the preceding figures of the drawing, attention is now directed,and in which figure the reference numerals of the preceding figures havebeen applied for the same parts.

In Fig. 6, tubes 18, 19 and 20 are con nected with their respectiveinput circuits through leads 21, and the various stages are coupled incascade through output leads 2'? and primary windings 28, each a sciatedwith an inductance winding 17. The first stage is supplied with signalenergy from any suitable source, such as an antenna 31 through a loadingcoil 32 and the input primary winding 30, and the amplified signalenergy is delivered through the two amplifier stages including tubes 18and 19 and the detector tube 20, to an output circuit including chokecoils 29 and an output terminal 33. Power terminals for operatingcurrents and voltages are indicated at I luded in circuit with certain.of such terminals is a volume control potentiometer or volume controldevice for controlling the screen grid potentials of the amplifier tubes18 and 19. The power circuit connections between the tubes are suitablylay-passed by fixed capacitors or condensers 36. These serve toconinlete the shielding of the circuits where they leave the variousstages and should be closely associated with each stage for which theyare provided.

The physical location of primary loading coil 32 is indicated in Figs. 1and 2, while town).

13m ns that of the volume control means is inbodying a high gain highfrequency amplifier using screen grid tubes and is shown only by way ofexample as being illustrative oi that type or" apparatus forwhich theshielding of the present invention is particularly adapted.

The essential elements with which the invention is concerned are theshielding and physical arrangement of the high frequency circuits of theapparatus, such as successive tuned stages involving inductances,tuningcapacities, high gain amplifier tubes, and the leads by which the coupfmeans or primary windings and the tuned circuits are connected with thetubes.

In an apparatus of the above character, a compact arrangement or" theabove named component parts is desirable .and necessary for modernreceiver design. This necessitates a close arrangement of parts wh ch,without shielding, or protection by metallic casings or walls, would beimpossible for electrical reasons. Electrical couplings, electrostatic,electromagnetic or both, between the tuned circuits of adjacent stages,as well as between the input and output circuits owl: the same stagemust be made as small possible. To provide shielding to accomplish thiswhich will be highly effective and which may be economicallymanufactured in quantity, involves a careful consideration of thecircuit components to be shielded.

Considering the circuit diagram of Fi 6 as an example of a circuit to beshielded or to be embodied in shielded receiving apparatus and the like,in accordance with the invention, a wall or shield represented by dottedline 38 may be placed between the input circuit and lead of each tube,and its output and power supply leads, which wall or shield will serveto electrically isolate the input of each tube from the output and powersupply leads thereof: By extending the shi lding by additional shields,for example by walls indicated by dotted lines 39 and 40, theinductances and condenser units of the tuned input circuits are shieldedfrom each other, that is the tuning elements or turned circuits of thevarious stages are shielded from each other.

In the present example, since the first stage is coupled to an openantenna, the tuning means for that stage is not necessarily shielded, asindicated. This is for the reason that, being exposed to externalelectrical influence through the medium of the antenna coupling,shielding would be relatively ineffective. The tuned circuits of theremaining stages and for the detector shielded from external electricalinfluences or forces, by the same shielding which :isolates them fromeach other.

In the circuit of the present example, the third tube, 20, is thedetector and accordingly does not require a shield between its input andoutput circuits. Itis obvious that shields may be added, in case thatthis tube functions in another amplifier stage, in the same manner asshield 38, asrepresented by the fine dotted line 41. Thediagrammaticrepresentation of the shielding is completed by a wallindicated by dotted line 40.

It will be noted that the. shielding a rangement as a whole is dividedinto compartments which are here designatedas-compartment-s A and 13,each compartment includ the elements providing one stage, that is, thetube with its output and supply leads and a tunedcircuit coupled withits output circuit or leads. In the case of compartment B which containsa tuned circuit connected with the detector, the detector tube 20 itselfis contained in the same coinpartment. \Vere it an amplifier tube,however, it would be isolated from the tuned input circuit by shieldingwall indicated by dotted line 41 :as above mentioned.

The shield'ing is so placed that it isolates or shields the controlelectrode terminal from the output circuit of an amplifier device ortube; in a multi-stage tuned high frequency amplifier it isolates orshields the tuned circuits, particularly the inductance's,

one from another, and it, shields the tuned' circuits and circuit means,particularly the inductances and the electric discharge devices, fromexternal electrical. influence. e, :such as shown diagrammatically 6 v Iin compartment A of Fig. 6 is not whollyin the section 01"" the physicalstructure, see Figs. 1.5. In order to accomplish the primary object ofthe invention, the tube or electric discharge device, with its outputand power supply leads, is physically located in the section with thepreceding stage, but shielded from that stage, as hereinafter described.

The shielding is thus'based upon an understanding heretofore not clearlydeveloped in the :art, of the ssential elements of an amplifier stagefor the purpose of applying effective shielding thereto in anu'lti-stageamplifier .apparaitus: To .provide such shieldii-ig each stage may bestbe considered to include the electric discharge device and its outputmeans, that is, its output circuit together with the necessary powersupply connections, and the means for transferring the amplified outputto a succeeding apparatus or device. In the present example this lastmeans is the tuned circuit associated with the output circuit of apreceding tube and providing the input circuit for the succeeding stage.A stage is therefore that apparatus contained in compartment A (Fig. 6)of the presentexample or compartment B, less the detector oroutput tube20.

Referring now to the preceding figures of the drawings in which theprinciples of shielding outlined diagrammatically in Fig. 6, are carriedout in a receiving apparatus, in accordance with the invention, therectangular frame for the multiple tuning capacitor is arranged tosupport the tube sockets 24in alignment with the tuning capacitorsections longitudinally of the frame, and laterally in alignment witheach other, providing parallel, laterally ext-ending rows of tuningcapacitor sections and tube sockets. The tuning inductances 17 for thevarious stages are arranged to occupy positions above and in spacedvertically aligned relation with their respective tuning capacitorsections, while the corresponding space aboveeach tube socket is adaptedto be occupied by the tube for a succeeding stage, when the apparatus isassembled for operation.

t will be seen that this arrangement of the parts or elements of theapparatus makes for a-high degree of compactness which is desirable inan apparatus of this character, and is best shown in Figs. 3, 4 and 5.It Will be noted that this arrangement permits the grid leads 21 to beshort and well spaced from other apparatus in all directions, that is,it provideslow ca'pacityto ground for these leads and avoids the morecommon use of piping or other enclosing means to shield these leads. V

The tube sockets and tuning capacitor are on substantially the samelevel in the frame while the tubes and inductances are, respectively,vertically above them. The coils or inductances, tuning capacitorsections, tube sockets and tubes for the various stages are thusphysically aligned in substantially parallel, vertical, longitudinallyextending planes and it will be seen without interfering with theelectrical circuit arrangement of the stages or their interconnection.With this physical arrangement and grouping of the various elements ofthe apparatus, shielding is readily applied thereto in accordance withthe principles outlined in connection with F ig. 6.

Within the confines of the frame 15, low vertical metallic walls 42cooperating with the Walls of the frame provide rectangular presentexample.

shielding walls 48 about the circuit terminal means or amplifier tubesockets 24 in the The well construction about the circuit terminals forthe tubes serves to shield each amplifier tube with its base output andpower supply leads from all parts not electrically associated withit asa stage or compartment, as defined in connection with Fig. 6 and theexplanation of it already given. In the present example, the detectorsocket terminals are not so shielded as it is found to be unnecessary.In connection with the detector tube socket shown, the wellconstructionis reduced to a transverse bar or bridge wall 44, arranged to form withcertain portions of the walls 42 of the socket wells which are alignedwith it, a bridge Wall which extends transversely across the framebetween the walls which carry the tuning control shaft bear ing, andparallel to the shaft between the tuning capacitor sections and the tubesock ets. This serves to brace the frame, and also to support the tuningcapacitor stators.

The frame is also divided longitudinally by parallel, vertical, metalpartitions 45, located between the stators. of the tuning capacitor andextending between the front and rear walls of the frame to shield saidstators one from another and to form in said frame a series of parallelrectangular openings 46, substantially at the level of the tuningcapacitor shaft, the partitions being notched as indicated at 47 toprovide slight clearances about the shaft.

The shield structure of the frame is completed by a closure means at thebottom in the form of a fiat metal base plate 48, se-

cured to the bottom of the frame in contact with the walls of the frameand the parti-' tions 42 and 45 as indicated in the drawings,particularly in Figs. 2 and 5. The plate is provided on its lower sidewith suitable supporting brackets 49 which serve as feet to support theapparatus when the plate is applied to the frame and to provide a spacebeneath the plate for mounting such apparatus as the can 37, Fig. 1. Thebrackets or feet on the frame serve not onlyas spacing are so located atthe edges of the base plate that they are also adapted to carryauxiliary apparatus such as the volume control potentiometer 35, Fig, 2,and its control -means indicated at 50, Fig. 1. For the sake ofsimplifying the drawings, this is not shown in Fig. 3, nor is the volumecontrol device shown except in Fig. 2 and as represented in Fig. 6. Oneof the brackets is shown in Figs. 4 and 5 and these figures togetherwith and supporting feet for the apparatus, but1-15 bottom of the frame.For example, the base plate may be provided integral with the frame,that is, the frame may be pro-, vided with a closed bottom wallrepresented by 1 late 48. As shown it merely represents a removable baseor bottom wall for the frame, and being removable servesto facilitatewiring or inspection of the interior of the frame from the bottom.

In the present example, the partitions 45 are integral with the frameand form a part of it as are also the walls 42 for the socket wells andthe transverse wall represented by the extension of wall 4%. Thisconstruction is easily carried out in manufacture by casting the entireframe structure above named in one piece of metal such as an alloy ofzinc, or aluminum.

lVith this construction, suitably spaced lugs or brackets 51, areprovided throughout the frame on the walls and partitions for thesupport of the sockets 2d, the tuning capacitor stators 9, 10 and 11 andthe base plate 48, as indicated in the drawings, particularly in Fig. 3.The lugs or brackets '51 are preferably cast integral with the frame andpartitions as indicated. The tube sockct bodies are of insulatingmaterial and are secured directly to the lugs 51 in the socket wellswhile the tuning capacitor stators are secured to strips of insulatingmaterial 52 which are in turn mounted upon suitably located lugs 51.

For the support of the inductances 17 simple ishaped metal brackets 53are .provided and secured ,at their ends to the base plate l8. Beingthus grounded to the metallic structure they serve as a combinedsupporting and grounding means for each inductance. one inductance leadbeing readily connected therewith indicated at 54, Fig. 1.

It will be seen from the foregoing description that the tube sockets areisolated from each other and from the tuning capacit r by walls aboutthe tube sockets, certain of the walls thereof forming a commonpartition wall which divides the frame transversely between the tuningcapacitor and the row of tube sockets; .thatthe frame ,is dividedlongitudinally by partitions between the tuning capacitor stators, whichshield the latter one from another, and which, together with the wallsof the frame, enclose the apparatus withinthe frame in a series ofsections having top openings, the bottoms of which sections are closedby a common base plate attached to the frame.

The tuning capacitor frame thus serves as a combined shield and baseunit or chassis for the apparatus, being provided in its side walls withbearings for the condenser shaft, with stator and socket supportingbrackets on its inner walls, with partitions PI'QVll .ag openings 46 forthe e 'iphcation of further shielding, andwith coil supporting Ineansinconnection with its basepla'te. The frame is strengthened and ,maderigid Pbyilts closed rectangular construction and by :the transverse andlongitudinal partitions Mounted .on the frame or chassisa're :aplurality of inverted sh elds or shield cam 55 adapted to be placed orer :the sockets 24 and being of a size and height to enclose :thetnbesand provide a shield bet-ween the :in put or control terminalconnection therefor, and the output and other socket or baseconnections. For this purpose the shields are provided with top openingsthrough which the tubes may project as indicated inl igs. 1, and 5.

The shields 55 are rectangular in shapein the present example, and areprovided w t-h flexible lower ed es 56 whereby they are adapted to bepressed into the socket "WBllS to a seated position against a .b eacl'o'T formed in each shield, about and s aced from i lower flexible edges.The socketwelis in the chassis thus serve :to close the bottoms ofthetube shields.

A plurality of similar inverted shields .or shield cans 58 are providedfor .the ,GOTISQI inductanees 1'7 and are similarly mounted upon theframe or chassis to surround said inductances and to shield them fromeach other and from external disturbances, These shields are providedwith flexible lower edges59 surrounded by abead orstop means ,60 and areofsuch rectangular shape that .they may be pressed with a tight fit to aseated position in the openings 4L6 :inthe chassis. The chassis'thusserves tosuppont the shields and the latter serve as closure means forthe openins 46 .therein. The shields 58 must be of such size and heightthat with the chassis they will completely enclose tube shields 55, thetubes and the tuning and in conjunction with .the chassis-section form aseries of enclosures or compartments A and B, Figs. 4 and 5,.fortihcsuccessive stages corresponding to the compartments as outlineddiagrammatically in input stage is not so shieldedin the presentexample, although it is obviousthat such shieldingmay be placed aboutit. 7 The coils or inductances are located wholly within separateindividual shields 58 although such shields have a common base.

NVzith this arrangement a double wall shield is provided between thecoils, Figs. 1, 2 and 5, which is more effective than asingle wall, andeach shield forms a lap joint with the chassis or base, providing {aneffective continuous shielding with the chassis. It will be noted thatthe cornersof the bottom edges .or skirts'56 and 59 of the shields orshield. cans 55' and 58, respectively arewcut away. This is not only togive -.the edges or skirts flexibility, but also to avoid the bossicapacitor section for each stage bility of poor or changeable contact inthe corners between the shields and the chassis, whereby contact noisesand irregular operation are avoided. Contact is thus made along thesides and ends of they shields and not at .the corners.

The larger or outer shields 58 are notched or recessed as indicated at61, corresponding to notches or recesses 47 in the partition walls tosurround the shaft 13 with a slight clearance space as indicated in thedrawings. At each recess 61, the larger or outer shields are providedwith spring clips or contacts, one of which is indicated at 62 in Fig.2. These contacts are adapted to engage the shaft 13 when the shieldsare seated on the chassis, and serve to connect the shields electricallywith the shaft by a better contact than that provided through the endbearings to the chassis.

Each circuit terminal well communicates with the adjacent compartment inthe direction of the output, or the compartment of the succeeding stagewith which the output leads are connected, through an opening 63 (Fig.4) in the adjacent longitudinal partition wall 45, and in one side ofthe well, as indicated in Figs. 3, 4 and 5. The output leads 27 may thusextend directly from the circuit terminals of the tube of one stage tothe primary winding 28 associated with the inductance 17 of the tunedoutput means for that stage (see Fig. 6). I This places the interior ofthe inner or tube shield and the socket terminal well in communicationthrough a shielded channel with the succeeding section or the inductanceshields (in the direction of the output) whereby the output and powersupply connections for the tube are electrically in the same compartmentwith the tuned circuit means or inductance associated with its output.

The shield maybe considered to include a few simple component parts such'as the chassis 15,'the outer removable portions 58 of the shield, andthe removable inner or tube shields 55. The latter are located withinthe larger shields to provide what may be considered to be a shieldwithin a shield. The chassis includes a simple rectangular frame,preferably of cast metal, divided by idinal partitions into a pluralityof sections. Each of the main sections is further divided by atransverse partition into two smaller sections. The longitudinalpartitions at shield the individual sections of the variable tuningcapacitor from each other and the transverse partitions at 42 shield thetube sockets from the variable tuning capacitor and from each other. Thechassis is therefore a partitioned and chambered frame having topopenings and shielded communication channels between the in teriorsections of the frame.

In the present example the two larger eration of apparatus embodyinghigh gain amplifier stages. I

It will be noted in Figs. 1 and 2 that while the shield cans 58 areprovided with lower edges 59 which are pressed into tight overlappingengagement with the frame or chassis, an additional holding down meansis provided in the form of a plate 64 of suitable form to en age thetops of shield cans 58 and is pressed down against them by suitableclamping means in the form of a pair of tie rods 65 mounted on the frame15 and provided with threaded upper ends on to each of which is screweda thumb nut 66. The plate is easily stamped from sheet metal and the tierods and thumb nuts are relatively inexpensive to manufacture.

The purpose of the holding down means is to prevent any slight movementof the shield cans 58 with respect to the chassis when the apparatus isin operation as it has been found that with high gain amplifiers anyslight movement of two abutting portions of the shielding may andusually does cause noises in the output of the apparatus. This isbelieved to be due, to changes in the resistance of the shielding pathto circulating currents flowing in the shielding.

Viewed in one of its aspects, the shielding system thus described may beconsidered to include a chambered apparatus base or chassis and a seriesof inductance chambered apparatus base or chassis and a series ofinductance and tube shields or shield cans mounted upon said base, eachinductance shield being in shielded communication through the base withone of the tube shields and each industance shield being arranged inconnection with the base to provide a shielded compartment to surroundand to enclose the tuning capacitor section associated with theinductance, along with another tube shield electrically isolated andshielded from the interior of said compartthe input of said tube isment,whereby located adjacent tlie'output lead from the tuned circuitprovided in the compartment.

Viewed in another of its aspects, the shielding system above describedmay be considered to include a rectangular pro- Viding an apparatuschassis and having a series of top openings with removableshield cansadapted to beseated in openings and providing lapped joints therewith toclose the same, and he base being adapted by the provision of suitablepartitions between said openings to cooperate with. the

shield cans to provide a series of closed compartments. Located in eachcompartment is an inductance, and a circuit terminal connection means,such as a tube socket, and

in at least one of said compartments is located an inner shielding meansinterposed between said inductance and the circuit terminal connectionmeans, such shielding means including a removable portion and a baseportion, the latter being in the form of' a circuit terminal shieldingwell and communicating with an adjacent compelment.

lVhat I claim as new and desire to secure by Letters Patent of theUnited States, is:

1. A shield for radio recei ing apparatus and the like including incombination, an open metallic frame having integral transverse andlongitudinal partitions dividing it into sections, a well in one of saidsections communicating with an adjacent section of said frame, aremovable shield mounted in said well, a second removable shield mounted on said frame and providing a closure means for said adjacentsection, and an enclosing means for one of said shields.

2. A shield for radio receiving apparatus and the like including incombination, a chambered apparatus base having a series of top openings,a series of shield mounted on said base and forming closure means forsaid openings, a second series of shield cans mounted on said base, atleast one of said last named shield cans being enclosed by one or saidlll'SL- named shield cans and being in shielded communi cation throughthe base with the interior of another of said first named shield cans.

3 A shield for radio receiving apparatus and the like including incombina ion, a chassis for said'apparatus, a plurality of shield cansmounted on said chassis for shielding electric discharge devices of theradio tube type, a plurality of inductance shield cans mounted on saidframe in spaced relation to each other, a plurality of spaced partitionsextending longitudinally across said chassis and arranged to cooperatewith said inductance shield to provide a plurality of shieldedcompartments, said partitions being arranged to provide openin 'sbetween said tube shield cans and s1 id ipartments.

s' ic d for radio receiving apparatus f ding in combination, a 'me ovid:K iihassis for lltl apparatus, plurality of open end shield cans mountedon said frame and adapted to provide shields for surrounding electricdischarge devices of the vacuum tube type, plurality of inductanceshield cans mounted on said frame in spaced relation to each o er, meansproviding a sh? --lded channel of 001m munication between one of saidtube shields and one of said inductance shields, ..a plu-' rality ofpartitions extending across said frame and arranged to cooperate withsaid inductance shield cans to provide a plurality of. shieldedcompartments, at least one of said tube shield cans being mounted withinone of said compartments.

5. A shield for radio receiving apparatus and the like including incombination, a rectangular metallic shield frame, a shaft extendingtransversely across said frame, bearings for said shaft in the end wallsof said frame, a plurality of longitudinally ex tending partitions insaid frame providing with the walls thereof a plurality of openings inthe frame, means for closing said openings and providing with the framea plurality of shielded compartments, walls in at least one of saidcompartments providing a well communicating with an ad jaceutcompartment, a circuit terminal means located in said well, and aremovable shield adapted to seat in said well and provide a shieldingenclosure about said circuit terminal means.

6. The combination with an electrical ap-- paratus including acircuittuning control "leans having a plurality of sections, a controlshaft therefor and a plurality of inductances cooperating with saidtuning control means to provide a plurality of tuned circuits, of ashielding means for said apparatus including an open metallic frameadapted to surround and support said tuning control means and shaft, apluralityof tube sockets mounted in said frame, walls integral with theframe providing wells about said tube sockets, partitions integral withthe frame extending between the sections of said tuning control means,means for supporting said inductances substantially vertically above andin spaced relation to each of said tuning control sections, a separateshield can adapted to surround each of said inductances and to engagethe frame with a lap-joint, said shield cans providing a double wallshield between one inductance and another and a closure means for theframe, and a tube shield I inountedin each of said socket wells. Y

7. The combination with an electrical apparatus including a circuittuning control means having a plurality of sections, a con trol shafttherefor and a plurality of inductances cooperating withsaid tuningcontrol means to provide a plurality of tuned circuits, of a shieldingmeans for said apparatus including an open metallic frame adapted tosurround and support said tuning control means and shaft, a plurality oftube sockets mounted in said frame, walls, providing wells about saidtube sockets, said walls being arranged to provide common Lee v .i nshield wall between said sockets and said sections of the tuning controlmeans, partitions extending between the sections of said tuning controlmeans and arranged to shield 1d sections of the tuning control means Momeach other, a separate shield can adapted to surround each of saidinductances and to engage said partitions with a lap-joint and form adouble wall shield between said inductances, individual tube shieldsadapted to be mounted in said socket wells to surround and shield a tubewhen mounted in the socket of said well, and a closure means for thebottom of said frame.

8, The combination with an electrical apparatus including a circuittuning control means having a plurality of sections, a control shafttherefor and a plurality of inductances cooperating with said tuningcontrol 162118 to provide a plurality of tuned circuits, of a shieldingmeans for said apparatus including an open metallic frame adapted tosurround and suppor said tuning control means and shaft, a plurality oftube sockets mounted in said frame, walls providing wells about saidtube sockets, said walls being arranged to provide a common shield wallbetween said sockets and said sections of the tuning control means,partitions extending between the sections of said tuning control meansand arranged to shield said sections of the tuning control means fromeach other, a separate shield can adapted to surround each of saidinductances and to engage the frame with a lap-joint, said shield cansproviding a double wall shield between one inductance and another and aclosure means for the frame, individual tube shields adapted to bemounted in said socket wells to surround and shield av tube when mountedin the socket of said well,,and a closure means for the bottom of saidframe, said means including a plate secured to the bottom of said frameand supporting feet for said frame arranged to provide a mounting spacebelow said frame.

1 9. The combination with a radio frequency amplifier of a shielding andsupporting means therefor, including a tuning capacitor frame, a baseconnected to said frame, partitions extending across said frame anddividing the same into sections, a bottom plate for said frame, shieldcans mounted on said partitions and providing covers for said sections,each of said shield cans forming with its corresponding resilient framesection and said base a shielded compartment, a plurality of tubeshields, and means for mounting each of said shields in the frame, atleast one of said means being located within the confines of one of saidsections whereby it is adapted to be enclosed by one of saidshieldedcompartments, and the interior of said shield mounting means being ncommunication with the interior of an ad acent section, I r 7 10. Thecombination with a tuning capacitor having a plurality of sections and acommon control shaft, a plurality of'inductances associated therewith,and tube sockets for a plurality of amplifier tubes, of a common supportand shielding means including a metallic frame for said tuning capacitorproviding bearings for said shaft and asupport for said. tube sockets,transverse and longitudinal metallic partitions in said frame arrangedto separate and shield said tube sockets and tuning capacitor sectionsfrom each other, a shield can adapted to surround and with the base toenclose an inductance, a tuning capacitor section and a tube. socket,and means for holding said can in a seated position on said frame.

11. In combination, a multiple tuning capacitor having a shaft, a framesupporting said shaft, a closure means for the bottom of the frame,individual removable closure means for the top of the frame, certain ofsaid last named closure means being adapted to cooperate with the frameto provide a series of closed shielded compartments, a tube terminalwell in one of said compartments communicating with an adjacentcompertinent, and a removable tube shield mounted on and forming aclosure means for said well. 7

12. In combination, a multiple tuning capacitor having a shaft, a framesupporting said shaft, a closure means for the bottom of the frame andindividual removable clo sure means for the top of the frame, certain ofsaid last named closure means being adapted to cooperate with the frameto provide a series of closed shielded compartments, a tube terminalwell in one of said compartments communicating with an adjacentcompartment, a removable tube shield mounted on and forming a closuremeans for said well, a tuning capacitor section located in each of said.shielded compartments, and an inductance coil connected and located inthe same compartment with each of said sections of the tuning capacitorto provide a series of tuned shielded circuits.

13. In a radio receiving apparatus, a me tallic base, a tuning controlmeans mounted on said base and including a series of individualsections, walls on said base extend ing between said sections to shieldthe latter one from another, an inductance coil ass0ciated with andmounted in spaced relation to each of said sections, a removablemetallic shield can mounted on said base in contact with said walls, andforming with the base a closed shielding compartment for oneof saidtuning capacitor sections and its associated inductance, means providinga shielded channel of communication between the interior of thecompartment and the ex terior thereof, walls providing a well w lin saidcompartment and in communication, and a shield for an electric dischargedevice arranged to provide a closure for said well within thecompartment.

14. In a radio receiving apparatus, a base, a tuning control meansmounted on said base and including a series of individual sections,Walls on said base extending between said sections to shield the latterone from another, an inductance coil associated with and mounted inspaced relation to each of said sections, a plurality of removablemetallic shield cans mounted on said base in contact with said walls,said cans being arranged to provide closure means for the base and withthe base a series of closed compartments, a tuning capacitor section andits associated inductance being located in each of said compartments,and said cans being spaced apart to provide a double wall shield betweensaid enclosed inductances, walls in one of said compartments providing acircuit terminal well communicating with an adjacent compartment, and ashield for an electric discharge device arranged to provide a closuremeans for said well.

15. A shield for radio receiving apparatus and the like including incombination, a metallic base providing a chassis for said apparatus andhaving a series of top openings, a plurality of removable shield canseach being adapted to seat in one of said top openings to close the sameand to provide with the chassis a series of shielded compartments, aninductance winding located in each of said compartments, a circuitterminal connection means located in one of said compartments, and aninner shielding means interposed between said circuit terminal means andthe inductance winding in said compartment, said shielding meansincluding a removable portion and a base portion, the latter being inthe form of a circuit terminal shielding well in communication with anadjacent compartiment.

In witness whereof, I have hereunto set my hand this 18th day ofFebruary, 1930. WILLIAM L. BOND.

